package QueueSecond.SwordOffer;

import java.util.LinkedList;
import java.util.List;

public class MovingAverage {
    /**
     * 剑指 Offer II 041. 滑动窗口的平均值
     * 给定一个整数数据流和一个窗口大小，根据该滑动窗口的大小，计算滑动窗口里所有数字的平均值。
     *
     * 实现 MovingAverage 类：
     *
     * MovingAverage(int size) 用窗口大小 size 初始化对象。
     * double next(int val) 成员函数 next 每次调用的时候都会往滑动窗口增加一个整数，请计算并返回数据流中最后 size 个值的移动平均值，即滑动窗口里所有数字的平均值。
     * 输入：
     * inputs = ["MovingAverage", "next", "next", "next", "next"]
     * inputs = [[3], [1], [10], [3], [5]]
     * 输出：
     * [null, 1.0, 5.5, 4.66667, 6.0]
     *
     * 解释：
     * MovingAverage movingAverage = new MovingAverage(3);
     * movingAverage.next(1); // 返回 1.0 = 1 / 1
     * movingAverage.next(10); // 返回 5.5 = (1 + 10) / 2
     * movingAverage.next(3); // 返回 4.66667 = (1 + 10 + 3) / 3
     * movingAverage.next(5); // 返回 6.0 = (10 + 3 + 5) / 3
     */
    /**
     * Initialize your data structure here.
     */

    LinkedList<Integer> list = new LinkedList<>();
    int size;
    double sum = 0;

    public MovingAverage(int size) {
        this.size = size;
    }

    public double next(int val) {
        if (list.size() < size) {
            sum += val;
            list.addLast(val);
            return sum / list.size();
        }
        int temp = list.removeFirst();
        sum -= temp;
        sum += val;
        list.addLast(val);
        return sum / size;  
    }

    public static void main(String[] args) {
        MovingAverage movingAverage = new MovingAverage(3);
        System.out.println(movingAverage.next(1));
        System.out.println(movingAverage.next(10));
        System.out.println(movingAverage.next(3));
        System.out.println(movingAverage.next(5));
    }
}
